21. The same, reddish and yellowish, fine-grained, rather friable. Wady Kawan.
22. Similar, reddish-brown variety of sandstone, but more friable than the preceding. Tadrart ridge.
23. The same, of a colour between grass and leek-green, fine-grained, very crumbling. “Traghen, under a gypsum crust; often in beds of from ten to twelve feet. It has the appearance of some of the soft sandstone in the mountain range near Tripoli.”
24. Yellowish-white friable sandstone, and fine sand, strongly impregnated with salt. “Under a calcareous crust, Fezzan.”
25. Similar sand of a very fine rounded grain. “From the Wady, in which is the Trona lake.”
26. Yellowish clayey sandstone, filled with small rounded quartz grains and minute white particles of small univalve shells, (Paludina?) “Gaaf.”
27. Fine and close-grained yellowish-white sandstone, of a thin stratified structure, which is distinctly seen at the disintegrated parts of the fragment. “Wady Katefa, under the basalt; forming fine precipitous walls in the middle of the range.”
28. Brownish-red friable sandstone; the rounded grains of various sizes, loosely united by clay. “Sandstone of the hills of Wady Ghrarbi. There is a finer and tender species, and also a stratiform one; but my specimens are lost.”
29. The same, of a similar colour, intermixed with yellowish, less crumbling, and containing pebbles. “From the hills to the westward of Hamera, on which the town is built.”
30. Sandstone of yellowish colour and fine-grained, faintly variegated with purple. Aghadem.